Check engine light is on intermitently on my 1998 legacy estate

Should change an air spring , make a shure diagnostic for air leaks on each air spring , hoses and valves with lather

Yes.
The speed sensor in the transmission gives the computer data to control fuel mixture and timing, and it also drives the speedo and odometer.
The sensor would need to be tested.

The switch is call backup light switch.

Inspect / clean the entire unit end to end.

Spray WD-40 or similar fluid on the plastic male and female socket ends to rule out bad contact points.

You may use a meter to check the socket for conductive resistance (when pressed)

I attached two pictures to help you identify the plastic socket that you need to disconnect and clean.
UK/International switch may look sightly different from USA version.

Remove / adjust this switch on level ground.
Transmission/gear fluid will leak out during removal.
MAKE SURE THE ENGINE and TRANSMISSION/GEAR BOX IS COLD before removal.
Top off / inspect all fluid level after switch installation.

This backup switch retail for around $45 USD.

Good luck

I have the same problem!Running on three.I have checked compression,wires,plugs.Changed injecters,plugs.
3 mech.cant figuire it out???

warm, cool control switch not working 

nee to test fuel injectors and watch engine electronics thru a scanner? another thing you might check is the airintake rubber bellows goes from air cleaner to engine for cracks or leaks? if all that checks out run a compression test ?

starter is going also check the relay

No.sounds like you have a fault with the air flow meter.

have you checked the knock sensor? This is a common issue with the older models it will give a rough idle and reduced gas mileage.

My car is doing same thing,

Caused by an Air lock in Auto Choke system

As soon as i put water into choke hose

seems to fix it then it does it again pain in ***